Advice? Acrylic baffles in glass sump

I know acrylic baffles in a glass sump aren't the ideal solution due to the bond (or lack thereof) between silicone and acrylic. However, I'm much more comfortable working with acrylic (I'll be routing weirs into baffles). I'm also not 100% set on things long term and would be more comfortable trying to cut acrylic back out of the sump. Also I'll have a bunch of live rock in the sump and would feel more comfortable with rock potentially bumping into acrylic from time to time.

It sounds like people have been able to make it work for sump baffles without many issues... my concern is regarding the thickness of the acrylic needed. I'm going to give the Triton sump design a try which calls for a large fuge in the first section of the sump... so I'm going for something like this:

I know this looks unconventional... I'm going to give it a try which is also one of the reasons I want the flexibility to ultimately change things back around if I hate it. I'm not concerned about the bubble trap baffles.. I'm more concerned with the weight the first baffle will have to support. Would 1/4" cell cast acrylic from Lowes be okay on that first section? Or is the 8" drop in water level going put too much pressure on the acrylic and/or the silicone? I could also silicone some small pieces of glass to the sides of the sump to support the acrylic if needed.
I really like the current dimensions since it meets the requirement of a fuge volume of 10% of the display and still allows enough empty space to allow my display to drain 4" before flooding the sump (I drop about 3" in a power outage).

Also, there are drilled holes on the bottom. What thickness of glass should I get to cover these? Any particular glass shop in the DSM area anyone recommends?

Any thoughts on this would be appreciated.

Thanks!

 

Thanks everyone! I'm picking up Momentive RTV from Grainger today. I was aware of the acrylic expansion.. didn't realize it took 16 weeks though!

Regarding the stagnant middle section, maybe I won't want to extend the second baffle which is supporting the eggcrate down so far. The skimmer return actually will go under the first baffle of the bubble trap... this is suggested by Triton to move the clean skimmed water out and leave the trapped proteins behind. The flow through the sump should be quite high (around 2500-3000 gph after head loss) so I'm hoping there won't be any issues.

 

Should the glass and acrylic be cleaned with something before applying silicone? Denatured alcohol, acetone, isopropyl alcohol?

 

Thanks! Any recommendations on a local glass shop? I'll just need a couple 1/4" pieces roughly 6" x 4" to cover the drilled holes on the bottom.

 

I'm wondering if I should go with 1/4" glass with 1/4" or 1/8" acrylic siliconed on top of it to patch the holes. It may sound kind of funny but I'm a little nervous about relying on such an important seal between glass and acrylic. I like the idea of the acrylic on top of the glass to help avoid cracking the 1/4" glass with any live rock in the sump. Along that line of thinking I'm wondering if I should put eggcrate along the bottom of the sump to avoid damage from rock directly sitting on the glass.

 

The tank I'm using for the sump was a reef ready tank. I managed to get the overflows cut out (that was a lot of fun) and cleaned the silicone using McKanica silicone remover:
McKanica® Silicone Caulk Remover Gel (0354) - Pure Silicone Caulk - Ace Hardware

I'll be prepping the edges of the baffles and the sides of the tank with denatured alcohol before I apply the silicone. Given that I have these products which I assume are quite toxic, is there something I should do to try to remove anything left behind? Or do the silicone remover and DA essentially off gas and neutralize after a period of time?

Thanks!

 

Rather than cutting teeth into the acrylic to try to strain out chaeto and other things from the refugium I've rigged up a screening mechanism with some gutter guard. I cut some 2" pieces of PVC which clips the gutter guard onto the top of the baffle. Looks good in theory.. hopefully this works out in practice.

 

My back hurts now. First baffle for the refugium is 3/8" thick with a 1/8" white panel bonded to it to try to contain/reflect light within the fuge. Other baffles are all 1/4". Hopefully it holds up! Oh yeah.. and cleaning up all of the acrylic shavings from cutting and routing was a lot of fun.

 

That was a fun little Sunday afternoon project.

Before:

After:

Everything seems to be running as expected and I didn't run into any major issues while swapping out the sump.